A cache of leaked documents obtained by the Guardian appears to show that Televisa, Mexico’s largest television company, which has recently been at the centre of a protest movement against media bias in the lead-up to the July 1 presidential elections, has a history of selling its editorial line to political interests.

The documents, presumed to be several years old, include outlines of fees that the television network apparently charged in exchange for giving favourable coverage to former Mexico state governor Enrique Peña Nieto on its news and entertainment programmes. The cache also includes a PowerPoint presentation with the stated aim of ensuring that leftwing candidate Manuel López Obrador did not win the 2006 elections, wrote the Guardian’s Jo Tuckman in an article published on Thursday. Peña Nieto is presently the frontrunner – by a wide but shrinking margin – in Mexico’s presidential race. López Obrador, who lost the elections in 2006, is his closest rival.